A process for producing an organosilicon resin is disclosed. The process includes the steps of equilibrating a mixture of silane compounds of Si(OR.sup.3).sub.4 wherein R.sup.3 's are a monovalent hydrocarbon group having 1 to 6 carbon atoms; R.sup.2 Si(OR.sup.4).sub.3 wherein R.sup.2 is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and R.sup.4 's are a monovalent hydrocarbon group having 1 to 6 carbon atoms; and R.sup.1.sub.3 SiX wherein X is an --OH group, an --OSiR.sup.1.sub.3 group or a hydrolyzable group, and R.sup.1 's are a monovalent hydrocarbon group having 1 to 6 carbon atoms; adding water to the product of the equilibration reaction to carry out hydrolysis reaction; and adding an aqueous alkali to the product of the hydrolysis reaction to carry out condensation reaction. The organosilicon resin obtained is well dispersible in a resin premix containing a polyol, a blowing agent, a catalyst and a foam stabilizer, and also is highly hydrophobic and low reactive. Hence, the resin premix containing the organosilicon resin has good storage stability. Accordingly, this resin premix need not be agitated when used and also can provide polyurethane foams having superior properties such as dimensional stability.